The top of a window should be as near the ceiling as practicable, because light entering the upper portion of a room illuminates it more evenly, and with less sharply marked shadows, than where the windows are lower down.
The walls below the windows should be sloped, in order that there may be no opportunity to use them as a resting place for material which should be placed elsewhere.
FIRE WALLS.
Brick division walls should be built so as to constitute a fire wall wherever it is practicable to do so. Such walls should project at least three feet above the roof, and should be capped by stone, terra cotta, or sheet metal. They must form a complete cut-off of all combustible material, especially at the cornices.
FIRE DOORS.
All openings in such walls must be provided with such fireproof doors as will prove reliable in time of need. Experience with iron doors of various forms of construction show that they have been utterly unreliable in resisting the heat of even a small fire. They will warp and buckle so as to open the passageway and allow the fire to pass through the doorway into the next room.
A door made of wood, completely enveloped by sheets of tinned iron, and strongly fastened to the wall, has proved to resist fire better than any door which can be applied to general use. I have seen such doors in division walls where they had successfully resisted the flame which destroyed four stories of a building filled with combustible material, without imposing any injury upon the door except the removal of the tin on the sheet iron; and the doors were kept in further service without any repairs other than a coat of paint.
The reason for this resistance to fire is that the wood, being a poor conductor of heat, will not warp and buckle under heat, and cannot burn for lack of air to support combustion. A removal of the sheet metal on such a door after a fire in a mill shows that the surface of the wood is carbonized, not burned, reduced to charcoal, but not to ashes.
Many fire doors are constructed and hung in such a manner that it is doubtful whether they could withstand a fire serious enough to require their services.
The door should be made of two thicknesses of matched pine boards of well dried stock, and thoroughly fastened with clinched nails. It should be covered with heavy tin, secured by hanging strips, and the sheets lock-jointed to each other, with the edge sheets wrapping around, so that no seam will be left on the edge.